1. Field of the Invention
The present invention relates to an electronic device. More specifically, the present invention relates to a semiconductor device with a plurality of memory cells stacked three-dimensionally.
2. Discussion of Related Art
A non-volatile memory element is a memory element that can get back stored data even when not powered. Recently, as the limit of enhancement of an integration degree of a two-dimensional memory element having memory cells formed on a silicon substrate in a single level is reached, a three-dimensional non-volatile memory element having memory cells stacked vertically on a silicon substrate has been proposed.
The three-dimensional non-volatile memory element includes interlayer insulating layers and word lines, which are alternately stacked, and channel layers, which pass therethrough. Memory cells are stacked along the channel layers. In the manufacturing process of the three-dimensional non-volatile memory element, the stacked word lines are formed by alternately stacking a plurality of oxide layers and a plurality of nitride layers and then replacing the plurality of nitride layers with a plurality of conductive layers.
However, the difficulty level of the process of replacing the plurality of nitride layers with the plurality of conductive layers is high. During the process of replacing the plurality of nitride layers with the plurality of conductive layers, other surrounding layers may be damaged, thereby degrading characteristics of the memory element.